The proposal to develop a GRC on Antigen Cross-presentation was borne out of the[unreadable] recognition that science in general has become too reductionist and hyper-specialized. The[unreadable] topic of antigen cross-presentation presents a research area that cuts across several scientific[unreadable] fields, including: Cell Biology; Cell Death; Dendritic Cell Immunobiology; Protein Folding; Lipid[unreadable] Biophysics; Signal Transduction; Antigen Processing and Presentation; and Translational[unreadable] Research including Tumor Immunology, Autoimmunity and Host / Pathogen Interactions. We[unreadable] recognize the need for increased interaction across these fields and see the GRC as an[unreadable] opportunity to build community and forge new collaborative efforts.[unreadable] [unreadable] Background: Cytotoxic T lymphocytes (CTLs) are an important component of the adaptive[unreadable] immune response. They destroy virally infected cells and are considered critical for the[unreadable] eradication of cells on their way toward malignant transformation. To become an effector cell[unreadable] and thus perform these tasks, CTLs must first be activated by an antigen presenting cell (APC)[unreadable] expressing MHC class I / peptide complexes on its cell surface. Classically, only antigen that is[unreadable] synthesized endogenously has access to the MHC I. This presumes direct infection of an APC[unreadable] is a pre-requisite for developing immunity to viruses; and excludes the possibility of generating[unreadable] immunity to tumor-restricted antigens. There is a growing body of evidence, however, which[unreadable] suggests that exogenous antigens can in fact be channeled into the MHC I presentation[unreadable] pathway of an APC for the activation of CTL. This phenomenon has been referred to as ?crosspriming?[unreadable] and the processing of exogenous antigen for MHC I presentation as ?crosspresentation.?[unreadable] The basic science aspects of how this pathway is regulated and the impact of[unreadable] these discoveries on disease pathogenesis and therapy is the focus of our new GRC.[unreadable] [unreadable] Aim: The aim of this conference is to achieve greater scientific interaction between the[unreadable] disciplines implicated in study of antigen cross-presentation. The program will focus on the[unreadable] physiologically relevant mechanisms that account for antigen transfer from non-hematopoetic[unreadable] cells to APCs. Specifically, we will consider heat shock proteins and immune complexes, which[unreadable] act as chaperones for antigen; as well as exosomes and dying cells, which represent efficient[unreadable] ways of packaging antigen for targeted delivery. In addition, we hope to push the envelope by[unreadable] including speakers on topics such as ubiquitination and intracellular transfer of MHC /peptide[unreadable] complexes. In all cases, we attempt to bridge the gap between researchers addressing[unreadable] questions using reductionist model systems with clinicians working at the bedside of patients.